The present invention relates to a top emission system light-emitting display and a method of manufacturing such a light-emitting display.
In recent years, as one of flat panel displays, organic EL displays displaying an image through the use of an organic EL (Electro Luminescence) phenomenon have received attention. The organic EL displays use the light-emitting phenomenon of an organic light-emitting device, so the organic EL displays have superior characteristics such as a wide viewing angle and low power consumption. Moreover, the organic EL displays have high responsivity to a high-definition high-speed video signal, so the organic EL displays has been developed toward practical use specifically in a video field or the like.
As a drive system in the organic EL displays, an active matrix system using a thin film transistor (TFT) as a drive element is superior in responsivity and resolution, compared to a passive matrix system, and in the organic EL displays having the above-described characteristics, the active matrix system is particularly considered as a suitable drive system. An active matrix type organic EL display includes a drive panel in which an organic EL element including an organic light-emitting layer and a drive element (the above-described thin film transistor) for driving the organic EL display element are arranged, and has a configuration in which the drive panel and a sealing panel are bonded together by an adhesive layer so that the organic EL element is sandwiched between the drive panel and the sealing panel. Moreover, the organic EL element has a configuration in which the organic light-emitting layer is formed between a pair of electrodes.
There are a bottom emission system organic EL display which emits light from each organic EL element to the above-described drive panel side and a top emission system organic EL display which emits the light to the opposite direction, that is, the above-described sealing panel side; however, the latter is a mainstream of development, because the latter can increase an aperture ratio.
Here, in the top emission system organic EL display, an electrode on a light extraction side, that is, on the sealing panel side is a common electrode for each organic EL element, and is made of, for example, a light-transmissive conductive material such as ITO (Indium Tin Oxide). However, such a light-transmissive conductive material has resistivity a few orders of magnitude higher than that in a typical metal material. Therefore, a voltage applied to the electrode on the light extraction side becomes nonuniform in a plane, so there is an issue that positional variations in light emission luminance among organic EL elements occur, and display quality declines.
Therefore, for example, Patent Document 1 discloses a technique in which an auxiliary wiring for being connected to an electrode on a light extraction side is formed of the same material as that of an electrode on a drive panel side in the same layer as the electrode on the drive panel side.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2002-318556